[5:27] Recite for them the true history of Adam's two sons. They made an offering, and it was accepted from one of them, but not from the other. He said, "I will surely kill you." He said, "GOD accepts only from the righteous.

[5:28] "If you extend your hand to kill me, I am not extending my hand to kill you. For I reverence GOD, Lord of the universe.

[5:29] "I want you, not me, to bear my sin and your sin, then you end up with the dwellers of Hell. Such is the requital for the transgressors."

[5:30] His ego provoked him into killing his brother. He killed him, and ended up with the losers.

[5:31] GOD then sent a raven to scratch the soil, to teach him how to bury his brother's corpse. He said, "Woe to me; I failed to be as intelligent as this raven, and bury my brother's corpse." He became ridden with remorse.

Grossness of Murder

[5:32] Because of this, we decreed for the Children of Israel that anyone who murders any person who had not committed murder or horrendous crimes, it shall be as if he murdered all the people. And anyone who spares a life, it shall be as if he spared the lives of all the people. Our messengers went to them with clear proofs and revelations, but most of them, after all this, are still transgressing.The authorized english translation of Quran by Rashad Khalifa

--------------------------
Everybody is born with a Jinn companion, the human should lead his companion, and shouldn't yield to his polytheistic whispers. In the case of the psychopath, his Jinn is in full control of his mind, this take over is not possible if the human is God-fearing and if he resist the temptation.